Bibha Chowdhury: A life spent in chasing cosmic rays

In Hindu mythology, the cosmic dance of Shiva symbolises the interplay of dynamic and static divine energy flow, containing the five principles of eternal energy — creation, preservation, destruction, illusion and emancipation. “Modern physics has... revealed that every sub-atomic particle not only performs an energy dance, but also is an energy dance; a pulsating process of creation and destruction.” -- Fritjof Capra (Austrian-born American physicist, systems theorist and deep ecologist)

It is not known what fascinated a little girl, born in the early year of the last century, to explore the complex mystery of the universe. Indian scientists have been working in the field of elementary particle physics and cosmic rays in India since the 1940s. The glorious period of Cosmic Ray research began in India during 1940s simultaneously in Calcutta, Lahore, Bangalore, Bombay, Ahmedabad and Aligarh. 

Debendra Mohan (D.M) Bose began his research at Calcutta University and then shifted to Bose Institute, where a host of young physicists joined him.  Piara Singh (P.S) Gill worked in the same sphere at Forman Christian College, Lahore and Homi Jehangir Bhabha initiated research at the Indian Institute of Science, Bangalore. Experimental research in cosmic rays in India got a big boost in 1945 with the establishment of Tata Institute of Fundamental Research (TIFR) by Homi J. Bhabha in Bombay. Vikram Sarabhai set up Physical Research Laboratory (PRL) in Ahmedabad in 1947 and P.S Gill established Cosmic Ray Laboratory at the Aligarh Muslim University (AMU) in 1949. TIFR has been the flagship for cosmic ray research in India.

But few Indians are aware of the pioneering work and contribution of Bibha Chowdhury (1913- 1991). She was the first woman particle physicist in India and, the first Indian woman to earn a Ph.D. in Physics. Unfortunately, her immense contributions to the field of particle physics remained unacknowledged throughout her lifetime. The brilliant physicist worked with some of the brightest   minds and stalwart scientists of her time including, Bhabha and Sarabhai at TIFR and PRL respectively and also in the laboratory of renowned British experimental physicist, Patrick Maynard Stuart (P.M.S) Blackett, known for his work on cloud chambers, cosmic rays, and paleomagnetism, who won the Nobel Prize for Physics in 1948. 

Bibha Chowdhury was born in a well-educated middle-class family in Calcutta in 1913. She was one of six siblings (five sisters and one brother). Her father, Banku Bihari Chowdhury was a physician and her mother, Urmila Devi was an emancipated lady who hailed from a liberal Brahmo family. Bibha too, was immensely influenced by the teachings of Brahmo Samaj. 

She was the only girl student in her MSc (Physics) class of 24 in the batch of 1934-36 in the physics department of Calcutta University. After her post-graduation, she joined the department for doing research under Debendra Mohan (D.M) Bose, who was the Palit Professor of Physics. Bose later moved to the Bose Science Institute (Bosu Bijnan Mandir) as its director, taking several of his research students, including Bibha Chowdhury with him.

At the Bose Institute, Chowdhury needed to work in the cloud chamber to determine the mass of cosmic particles but due to some technical snag, the machine was defunct and Chowdhury searched for an alternative and came across Austrian physicist Marietta Blau’s discovery. She had developed photographic nuclear emulsions that were usefully able to image and accurately measure high-energy nuclear particles and events, significantly advancing the field of particle physics in her time. When this discovery was discussed at the Indian Science Congress conference, DM Bose advised Bibha to use photographic plates. She did so and discovered mesons using photographic plates. Mesons are sub-atomic particles that are unstable and decay in few hundredth of a second. Bose and Bibha took the photographic plates to Darjeeling, Sandakphu and an area called Phari Jung near the Bhutan border for research.

Was it a classic case of gender discrimination? Two leading science historians, Rajinder Singh and Suprakash C Roy have sought to answer this question in their book, ‘A jewel unearthed: Bibha Chowdhury’. “Here gender discrimination means that she was not elected as member of any of the three science academies though her work was of high quality. Chowdhury’s name does not figure anywhere in the writing on cosmic particle research done at KGF,” insists Dr Rajinder Singh, who teaches at the University of Oldenburg in Germany.

Between 1938 and 1942, Chwodhury and Bose jointly published three consecutive articles in ‘Nature’, the world's leading multi-disciplinary science journal. However, they could not follow up on the meson research due to unavailability of sensitive photographic emulsion plates necessary for experiments during the global crisis following World War II. In fact, C.F. Powell, an English Physicist, made the same discovery using similar methods a few years later for which he was awarded the Nobel Prize. Bibha, thus, missed her tryst with history!

Bibha was raring to continue her research but when faced with acute funding and material shortages due to the ongoing war, she moved to University of Manchester in 1945. There she worked in the lab of Prof. P.M.S. Blackett for her Ph.D. There she conducted research on cosmic rays (high energy radiation originating outside the Solar System) and air showers (showers of ionized particles when cosmic rays enter the atmosphere). Her doctoral thesis was on “extensive air showers associated with penetrating particles.” She defended her thesis in 1949. Meanwhile, Prof. Blackett went on to win the Nobel Prize in Physics for his work on cosmic rays. 

Since Homi J. Bhabha was also working in the same field, he made enquiries with one of Chowdhury’s thesis examiners about her and finally recruited her to join TIFR. She was the first woman researcher to do so in 1949, and remained there till 1957. M G K Menon and Yash Pal were her contemporaries at TIFR where she was involved in finding several types of k-mesons using nuclear emulsion stacks interspersed with brass plates. She also participated in the international conference on elementary particle held at Pisa in Italy in 1955, along with colleagues from TIFR.

But few Indians are aware of the pioneering work and contribution of Bibha Chowdhury (1913- 1991). She was the first woman particle physicist in India and, the first Indian woman to earn a Ph.D. in Physics. Unfortunately, her immense contributions to the field of particle physics remained unacknowledged throughout her lifetime. The brilliant physicist worked with some of the brightest minds and stalwart scientists of her time including,

From the beginning of 1960, Chowdhury joined as a core member of the team that conducted the proton decay experiment in the Kolar Gold Fields (KGF) under M G K Menon’s leadership. After she moved to PRL, she proposed another experiment at Mount Abu in Rajasthan. She wanted to study radio frequency emissions associated with extensive air showers. But after PRL Director Vikram Sarabhai’s demise, the direction of research programmes changed and PRL cancelled her proposal. This was a blow for her and she opted for voluntary retirement and moved back to academic and research work in Calcutta.

Bibha was involved in research work at the Saha Institute of Nuclear Physics and the Indian Association for the Cultivation of Science. During her long and illustrious career in physics spanning decades, Chowdhury published several research papers in international journals. She remained a life-long researcher, and the last paper co-authored by her was published in the Indian Journal of Physics in 1990 – a year before she passed away.

Although Chowdhury worked in tandem with some of the pioneers of the physics fraternity in India and abroad, she has remained in the shadows as an unsung hero of Indian science. It would be an understatement to say that the conditions were tough for Bibha during her time. Her supervisor, D.M. Bose was hesitant to employ women, in spite of Bibha showing her mettle and publishing in prestigious journals. She was not elected to fellowship of any of the three celebrated science academies in Indian nor named for any major prize. 

Was it a classic case of gender discrimination? Two leading science historians, Rajinder Singh and Suprakash C Roy have sought to answer this question in their book, ‘A jewel unearthed: Bibha Chowdhury’. “Here gender discrimination means that she was not elected as member of any of the three science academies though her work was of high quality. Chowdhury’s name does not figure anywhere in the writing on cosmic particle research done at KGF,” insists Dr Rajinder Singh, who teaches at the University of Oldenburg in Germany. The book quotes studies to point out that only 3.3 per cent of Fellows of the Indian National Science Academy (INSA) in physics were women till 2012. A book on Indian women scientists featuring 100 of them from Victorian to present times, published by the Bangalore-based Indian Academy of Sciences, did not include Chowdhury. Dr Singh says, “We have no definite answer regarding her being overlooked for promotion etc, (at PRL) but there is indirect evidence of discrimination.”

However, recently two posthumous honours have been bestowed on Chowdhury. The International Astronomical Union named a yellow white dwarf star as Bibha in 2018 and in 2020 the Government of India declared a chair professorship in her name to be established in the Tata Institute of Fundamental Research (TIFR) or in the Physical Research Laboratory (PRL). Her life story is exemplary and inspirational to younger generations.